Cement slurries, cured cements and methods of making and use thereof

ABSTRACT

Cement slurries, cured cements, and methods of making cured cement and methods of using cement slurries are provided. The cement slurry contains water, a cement precursor material, an alcohol surfactant having from 10 to 20 carbon atoms and a carboxylic acid comprising an aliphatic chain having from 16 to 18 carbons. In some embodiments, the alcohol surfactant may comprise the formula R—(OC 2 H 4 ) x —OH where R is a hydrocarbyl group having from 10 to 20 carbons and x is an integer from 1 to 10. The cured cement contains water, cement, an alcohol surfactant having from 10 to 20 carbon atoms and a carboxylic acid comprising an aliphatic chain having from 16 to 18 carbons. In some embodiments, the alcohol surfactant may comprise the formula R—(OC 2 H 4 ) x —OH where R is a hydrocarbyl group having from 10 to 20 carbons and x is an integer from 1 to 10.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is filed as a continuation of U.S. application Ser. No.15/628,895 filed on Jun. 21, 2017, which claims the benefit of U.S.Provisional Patent Application Ser. No. 62/454,189 filed Feb. 3, 2017(SA 6100 MA) and U.S. Provisional Patent Application Ser. No. 62/454,192filed Feb. 3, 2017 (SA 6101 MA), all of which are incorporated byreference herein in their entirety.

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to cementslurries and methods of making and using cement slurries, and to curedcements and methods of making cured cement. Specifically, embodiments ofthe present disclosure relate to cement slurries and cured cementshaving an alcohol surfactant and a carboxylic acid, and methods ofmaking and using cement slurries and cured cements having an alcoholsurfactant and a carboxylic acid.

BACKGROUND

Cement slurries are used in the oil and gas industries, such as forcementing in oil and gas wells. Primary, remedial, squeeze, and plugcementing techniques can be used, for instance, to place cement sheathsin an annulus between casing and well formations, for well repairs, wellstability, for well abandonment (sealing an old well to eliminate safetyhazards), and many other applications. These cement slurries must beable to consistently perform over a wide range of temperatures andconditions, as oil and gas wells can be located in a multitude ofdiverse locations. For example, a cement slurry may be used inconditions of from below 0° in freezing permafrost zones, and intemperatures exceeding 400° C. in geothermal wells and, as such, must beable to properly set under an assortment of conditions.

Proper hardening of a cement slurry can be vital to the strength andperformance properties of the cured cement composition. However,conventional cement solutions have poor flowability due to the viscousnature of the slurry, creating concerns when handling or pumping thecement, as uniform placement of the slurry can be quite difficult.Moreover, cement slurries are often incompatible with other fluids thatmay be present in the casing or the wellbore wall, such as drillingfluids, and prolonged contact could cause the cement slurry to gel,preventing proper placement and removal of the cement. Additionalproblems are encountered when curing a cement slurry into a curedcement. Cement slurries often cure through water-based reactions and,thus, too much or too little water loss can negatively impact thehardening process. Water may be lost or gained due to inclement weather,the conditions of the soil surrounding the well, or a multitude of otherfactors.

SUMMARY

Accordingly, there is an ongoing need for cement slurries having goodflowability and pumpability with improved fluid loss control and forcured cement compositions that have cured uniformly without unwantedadditional additives or artificially created conditions. The presentembodiments address these needs by providing cement slurries and methodsof making and using cement slurries that have improved rheology andfluid loss control, and cured cements and methods of making cured cementthat cures uniformly with improved hardness and good wettability.

In one embodiment, cement slurries are provided, which contain water, acement precursor material, an alcohol surfactant having from 10 to 20carbon atoms, and a carboxylic acid having from 16 to 18 carbon atoms.The alcohol surfactant may have a hydrophilic -lipophilic balance (HLB)of from 12 to 13.5. In some embodiments, the alcohol surfactant maycomprise the formula R—(OC₂H₄)_(x)—OH, where R is a hydrocarbyl groupcomprising 10 to 20 carbon atoms and x is an integer from 1 and 10.

In another embodiment, cured cements are provided in which the curedcement contains an alcohol surfactant having from 10 to 20 carbon atoms,and a carboxylic acid having from 16 to 18 carbon atoms. The alcoholsurfactant may have an HLB of from 12 to 13.5. In some embodiments, thealcohol surfactant may comprise the formula R—(OC₂H₄)_(x)—OH, where R isa hydrocarbyl group comprising 10 to 20 carbon atoms and x is an integerfrom 1 and 10.

In another embodiment, methods of producing a cured cement are provided.The methods include mixing water with a cement precursor, an alcoholsurfactant having from 10 to 20 carbon atoms, and a carboxylic acidhaving from 16 to 18 carbon atoms. The alcohol surfactant may have anHLB of from 12 to 13.5. In some embodiments, the alcohol surfactant maycomprise the formula R—(OC₂H₄)_(x)—OH, where R is a hydrocarbyl groupcomprising 10 to 20 carbon atoms and x is an integer from 1 and 10. Themethod further includes curing the cement slurry into a cured cement.

In another embodiment, methods of cementing a casing a wellbore areprovided. The methods include pumping a cement slurry into an annulusbetween a casing and a wellbore. The cement slurry includes water, acement precursor material, an alcohol surfactant having from 10 to 20carbon atoms, and a carboxylic acid having from 16 to 18 carbon atoms.The alcohol surfactant may have an HLB of from 12 to 13.5. In someembodiments, the alcohol surfactant may comprise the formulaR—(OC₂H₄)_(x)—OH, where R is a hydrocarbyl group comprising 10 to 20carbon atoms and x is an integer from 1 and 10. The method furtherincludes curing the cement slurry to cement the casing in the wellbore.

Additional features and advantages of the described embodiments will beset forth in the detailed description which follows, and in part will bereadily apparent to those skilled in the art from that description orrecognized by practicing the described embodiments, including thedetailed description which follows as well as the claims.

DETAILED DESCRIPTION

Embodiments of the present disclosure relate to cement slurries andmethods of making and using cement slurries that have, among otherattributes, improved rheology, such as improved flowability andpumpability. As used throughout the disclosure, “cement slurry” refersto a composition comprising a cement precursor that is mixed with atleast water to form cement. The cement slurry may contain calcinedalumina (Al₂O₃), silica (SiO₂), calcium oxide (CaO, also known as lime),iron oxide (FeO), magnesium oxide (MgO), clay, sand, gravel, silicasand, silica flour, manganese tetroxide, and mixtures of these.Embodiments of the present disclosure also relate to methods ofproducing and using cement slurries, in some particular embodiments, foruse in the oil and gas industries. Still further embodiments of thepresent disclosure relate to cured cements and methods of producingcured cements. As used throughout this disclosure, “cured cement” refersto the set, hardened reaction product of the components of a cementslurry.

As a non-limiting example, the cement slurries and cured cementcompositions of the present disclosure may be used in the oil and gasdrilling industries, such as for cementing in oil and gas wells. Oil andgas wells may be formed in subterranean portions of the Earth, sometimesreferred to as subterranean geological formations. The wellbore mayserve to connect natural resources, such as petrochemical products, to aground level surface. In some embodiments, a wellbore may be formed inthe geological formation, which may be formed by a drilling procedure.To drill a subterranean well or wellbore, a drill string including adrill bit and drill collars to weight the drill bit is inserted into apredrilled hole and rotated to cut into the rock at the bottom of thehole, producing rock cuttings. Commonly, drilling fluid, known as“drilling mud,” may be utilized during the drilling process. To removethe rock cuttings from the bottom of the wellbore, drilling fluid ispumped down through the drill string to the drill bit. The drillingfluid cools the drill bit and lifts the rock cuttings away from thedrill bit and carries the rock cuttings upwards as the drilling fluid isrecirculated back to the surface.

In some instances, a casing may be inserted into the wellbore. Thecasing may be a pipe or other tubular structure which has a diameterless than that of the wellbore. Generally, the casing may be loweredinto the wellbore such that the bottom of the casing reaches to a regionnear the bottom of the wellbore. In some embodiments, the casing may becemented by inserting a cement slurry into the annulus region betweenthe outer edge of the casing and the edge of the wellbore (the surfaceof the geological formation). The cement slurry may be inserted into theannular region by pumping the cement slurry into the interior portion ofthe casing, to the bottom of the casing, around the bottom of thecasing, into the annular region, or a combination of some or all ofthese. The cement slurry may displace the drilling fluid, pushing it tothe top of the well. In some embodiments, a spacer fluid may be used asa buffer between the cement slurry and the drilling fluid by displacingand removing the drilling fluid before the cement slurry is pumped intothe well to prevent contact between the drilling fluid and the cementslurry. Following the insertion of an appropriate amount of cementslurry into the interior region of the casing, in some embodiments, adisplacement fluid may be utilized to push the cement slurry out of theinterior region of the casing and into the annular region. Thisdisplacement may cause the entirety of the spacer fluid and drillingfluid to be removed from the annular region, out the top of thewellbore. The cement slurry may then be cured or otherwise allowed toharden.

To ensure the stability and safety of a well, it is important that thecement slurry properly harden into cured cement. If the cement slurry isnot evenly placed or fluid is lost from the cement slurry before curing,the cement slurry may not evenly harden into a cured cement. Therefore,the viscosity and flowability of a cement slurry is important to ensureproper placement. Similarly, reducing fluid loss from the cement slurryensures uniform hardening, as curing often involves water-basedreactions with the cement slurry. Too much or too little water affectsthe hardness and, thus, the quality of the cured cement produced.

A number of conditions may impact the fluid loss of a cement slurry. Forinstance, water may be drawn from the slurry into the permeableformation, particularly if pumping ceases and the slurry becomes staticwithout hardening. Water may also be lost due to displacement as thecement slurry is passed through constrictions, such as the tightclearance between a casing and an annulus, which may “squeeze” waterfrom the slurry. Adverse weather and soil conditions may additionalimpact the amount of water present in the cement slurry. As such,control of fluid loss of the cement slurry may allow for a more uniformand stronger cured cement.

The present disclosure provides cement slurries which may have, amongother attributes, improved rheology and reduced fluid loss, to addressthese concerns. The cement slurry of the present disclosure includeswater, a cement precursor material, an alcohol surfactant, and acarboxylic acid. Without being bound by any particular theory, use ofthe alcohol surfactant along with the cement precursor material andcarboxylic acid, in some embodiments, may provide reduced viscosity ofthe cement slurry to allow for easier processing, flowability, andhandling of the cement slurry in various applications. In someembodiments, use of the alcohol surfactant along with the cementprecursor material and carboxylic acid may provide reduced water contentin the cement slurry, reduced fluid loss, and, in some embodiments, mayreduce the friction pressure of the cement slurry to aid in drying andcuring the cement slurry. In some embodiments, use of the alcoholsurfactant along with the cement precursor material and carboxylic acidmay additionally improve efficiency and performance of other optionaladditives, such as fluid loss additives.

The cement precursor material may be any suitable material which, whenmixed with water, can be cured into a cement. The cement precursormaterial may be hydraulic or non -hydraulic. A hydraulic cementprecursor material refers to a mixture of limestone, clay and gypsumburned together under extreme temperatures that may begin to hardeninstantly or within a few minutes while in contact with water. Anon-hydraulic cement precursor material refers to a mixture of lime,gypsum, plasters and oxychloride. A non-hydraulic cement precursor maytake longer to harden or may require drying conditions for properstrengthening, but often is more economically feasible. A hydraulic ornon-hydraulic cement precursor material may be chosen based on thedesired application of the cement slurry of the present disclosure. Insome embodiments, the cement precursor material may be Portland cementprecursor. Portland cement precursor is a hydraulic cement precursor(cement precursor material that not only hardens by reacting with waterbut also forms a water-resistant product) produced by pulverizingclinkers, which contain hydraulic calcium silicates and one or more ofthe forms of calcium sulfate.

The cement precursor material may include one or more of calciumhydroxide, silicates, oxides, belite (Ca₂SiO₅), alite (Ca₃SiO₄),tricalcium aluminate (Ca₃Al₂O₆), tetracalcium aluminoferrite(Ca₄Al₂Fe₂O₁₀), brownmilleriate (4CaO.Al₂O₃.Fe₂O₃), gypsum (CaSO₄.2H₂O)sodium oxide, potassium oxide, limestone, lime (calcium oxide),hexavalent chromium, calcium alluminate, other similar compounds, andcombinations of these. The cement precursor material may includePortland cement, siliceous fly ash, calcareous fly ash, slag cement,silica fume, any known cement precursor material or combinations of anyof these.

In some embodiments, the cement slurry may contain from 10% BWOC (ByWeight Of Cement) to 90% BWOC, or 25% to 75% BWOC, or 40% to 60% BWOC ofthe cement precursor material based on the total weight of the cementslurry. The cement may contain from 28 to 810 pounds per barrel (lb/bbl)of the cement precursor material based on the total weight of the cementslurry. For instance, the cement slurry may contain from 30 to 800lb/bbl, from 50 to 800 lb/bbl, from 100 to 800 lb/bbl, from 30 to 500lb/bbl or from 30 to 300 lb/bbl.

Water may be added to the cement precursor material to produce theslurry. The water may be distilled water, deionized water, or tap water.In some embodiments, the water may contain additives or contaminants.For instance, the water may include freshwater or seawater, natural orsynthetic brine, or salt water. In some embodiments, salt or otherorganic compounds may be incorporated into the water to control certainproperties of the water, and thus the cement slurry, such as density.Without being bound by any particular theory, increasing the saturationof water by increasing the salt concentration or the level of otherorganic compounds in the water may increase the density of the water,and thus, the cement slurry. Suitable salts may include, but are notlimited to, alkali metal chlorides, hydroxides, or carboxylates. In someembodiments, suitable salts may include sodium, calcium, cesium, zinc,aluminum, magnesium, potassium, strontium, silicon, lithium, chlorides,bromides, carbonates, iodides, chlorates, bromates, formates, nitrates,sulfates, phosphates, oxides, fluorides, and combinations of these. Insome particular embodiments, brine may be used as the water.

In some embodiments, the cement slurry may contain from 10 wt. % to 70wt. % water based on the total weight of the cement slurry, or 10 wt. %to 50 wt. % in further embodiments. The cement slurry may contain from28 to 450 lb/bbl water based on the total weight of the cement slurry.For instance, the cement slurry may contain from 50 to 450 lb/bbl, from50 to 400 lb/bbl, from 75 to 450 lb/bbl, from 100 to 400 lb/bbl, from100 to 300 lb/bbl, or from 200 to 450 lb/bbl water.

Along with the cement precursor material and water, the cement slurrymay include at least one alcohol surfactant. A surfactant refers to acompound that lowers the surface tension or interfacial tension betweentwo or more liquids or between a liquid and a solid. As used throughoutthis disclosure, an “alcohol surfactant” refers to a surfactant havingat least one hydroxy group (—OH) or at least one hydroxyl moiety (OH)that is bound to a carbon atom. The alcohol surfactant may beamphiphilic, meaning that it has a hydrophobic tail (such as a non-polarR group) and a hydrophilic head (such as a polar —OH group).

In some embodiments, the alcohol surfactant may contain from 10 to 20carbons, such as from 10 to 18 carbons, from 10 to 16 carbons, from 10to 14 carbons, or from 10 to 12 carbons. The alcohol surfactant may havefrom 11 to 20 carbons, from 13 to 20 carbons, from 15 to 20 carbons,from 17 to 20 carbons, from 10 to 15 carbons, or from 12 to 15 carbons,or from 12 to 14 carbons. In some embodiments, the alcohol surfactantmay have 12 carbons, 13 carbons, 14 carbons or 15 carbons. In someembodiments, the alcohol surfactant may be an ethoxylated alcoholsurfactant. The alcohol surfactant may be a fatty alcohol ethoxylate,and may be a non-ionic surfactant.

According to one or more embodiments, the alcohol surfactant may havethe chemical structure of Formula (I):

R—(OC₂H₄)_(x)—OH   Formula (I)

In Formula (I), R is a hydrocarbyl group having from 10 to 20 carbonatoms and x is an integer from 1 to 10. As used in this disclosure, a“hydrocarbyl group” refers to a chemical group consisting of carbon andhydrogen. Typically, a hydrocarbyl group may be analogous to ahydrocarbon molecule with a single missing hydrogen (where thehydrocarbyl group is connected to another chemical group). Thehydrocarbyl group may contain saturated or unsaturated carbon atoms inany arrangement, including straight (linear), branched, aromatic, orcombinations of any of these configurations. The hydrocarbyl R group insome embodiments may be an alkyl (—CH₃), alkenyl (—CH═CH₂), alkynyl(—C≡CH), or cyclic hydrocarbyl group, such as a phenyl group, which maybe attached to a hydrocarbyl chain.

In one or more embodiments, R may include from 10 to 20 carbons, such asfrom 10 to 18 carbons, from 10 to 16 carbons, from 10 to 14 carbons, orfrom 10 to 12 carbons. R may have from 11 to 20 carbons, from 13 to 20carbons, from 15 to 20 carbons, from 17 to 20 carbons, from 10 to 15carbons, or from 12 to 15 carbons, or from 12 to 14 carbons. In someembodiments, R may have 12 carbons, 13 carbons, 14 carbons or 15carbons. In some particular embodiments, R may have 13 carbons, and, insome embodiments, R may be C₁₃H₂₇ (iso tridecyl).

In Formula (I), x is an integer between 1 and 10. In some embodiments, xmay be 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. In some embodiments, x may bean integer from 5 to 10, from 5 and 9, from 7 to 10, or from 7 to 9. Insome embodiments, x may be an integer greater than or equal to 5, suchas an integer greater than or equal to 7, or greater than or equal to 8.

As mentioned, the alcohol surfactant may be amphiphilic, meaning that ithas a hydrophobic tail (the non-polar R group) and a hydrophilic head(the polar —OH groups from ethylene oxide and the alcohol group) thatmay lower the surface tension between two liquids or between a liquid.In some embodiments, the alcohol surfactant may have ahydrophilic-lipophilic balance (HLB) of from 12 to 13.5. Without beingbound by any particular theory, the HLB of the compound is the measureof the degree to which it is hydrophilic or lipophilic, which may bedetermined by calculating values for the regions of the molecules inaccordance with the Griffin Method in accordance with Equation 1:

$\begin{matrix}{{HLB} = {20 \times \frac{M_{h}}{M}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In Equation 1, M_(h) is the molecular mass of the hydrophilic portion ofthe molecule and M is the molecular mass of the entire molecule. Theresulting HLB value gives a result on a scale of from 0 to 20 in which avalue of 0 indicates to a completely hydrophobic/lipophilic molecule anda value of 20 corresponds to a completely hydrophilic/lipophobicmolecule. Generally, a molecule having an HLB of less than 10 islipid-soluble (and thus water-insoluble) and a molecule having an HLB ofgreater than 10 is water-soluble (and thus lipid-insoluble).

In some embodiments, the alcohol surfactant may have an HLB of from 12to 13.5. The alcohol surfactant may have an HLB of from 12 to 13, from12.5 to 13.5, from 12.25 to 13.5, from 12.25 to 13, from 12.25 to 13.25,or from 12.25 to 12.75. In some embodiments, the alcohol surfactant mayhave an HLB of 12, 12.5, 12.75, 13, 13.25, or 13.5. This HLB value mayindicate that the alcohol surfactant has both hydrophilic and lipophilicaffinities (as the surfactant is amphiphilic) but has a slightly greatertendency towards being hydrophilic/lipophobic, and thus, may bewater-soluble.

The cement slurry may contain from 0.01% BWOC to 10% BWOC of thesurfactant based on the total weight of the cement slurry. The cementslurry may contain from 0.02 to 90 lb/bbl of the surfactant based on thetotal weight of the cement slurry. For instance, the cement slurry maycontain from 0.1 to 90 lb/bbl, from 0.1 to 75 lb/bbl, from 0.1 to 50lb/bbl, from 1 to 90 lb/bbl, from 1 to 50 lb/bbl, from 5 to 90 lb/bbl,or from 5 to 50 lb/bbl of the surfactant.

The alcohol surfactant may be a reaction product of a fatty alcoholethoxylated with ethylene oxide. As used throughout the disclosure, a“fatty alcohol” refers to a compound having a hydroxyl (—OH) group andat least one alkyl chain (—R) group. The ethoxylated alcohol compoundmay be made by reacting a fatty alcohol with ethylene oxide. Theethoxylation reaction in some embodiments may be conducted at anelevated temperature and in the presence of an anionic catalyst, such aspotassium hydroxide (KOH), for example. The ethoxylation reaction mayproceed according to Equation 2:

$\begin{matrix}{{{ROH} + {x\; C_{2}H_{4}O}}\overset{KOH}{\rightarrow}{{R\left( {{OCH}_{2}{CH}_{2}} \right)}_{x}{OH}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

The fatty alcohols used as the reactant in Equation 2 to make theethoxylated alcohol compound could include any alcohols having formulaR—OH, where R is a saturated or unsaturated, linear, or branchedhydrocarbyl group having from 10 to 20 carbon atoms, from 10 to 16carbon atoms, or from 12 to 14 carbon atoms. In some embodiments, R maybe a saturated linear hydrocarbyl group. Alternatively, the fattyalcohol may include R that is a branched hydrocarbyl group.

In some embodiments, the R—OH group of the surfactant may be anaturally-derived or synthetically-derived fatty alcohol. Non-limitingexamples of suitable fatty alcohols may include, but are not limited tocapryl alcohol, perlargonic alcohol, decanol (decyl alcohol), undecanol,dodecanol (lauryl alcohol), tridecanol (tridecyl alcohol), myristylalcohol (1-tetradecanol), pentadecanol (pentadecyl alcohol), cetylalcohol, palmitoleyl alcohol, heptadecanol (heptadecyl alcohol) stearylalcohol, nonadecyl alcohol, arachidyl alcohol, other naturally-occurringfatty alcohols, other synthetic fatty alcohols, or combinations of anyof these. In some particular embodiments, the fatty alcohol may includedecanol (decyl alcohol) or tridecanol (tridecyl alcohol).

The fatty alcohol may be a naturally occurring fatty alcohol, such as afatty alcohol obtained from natural sources, such as animal fats orvegetable oils, like coconut oil. The fatty alcohol may be ahydrogenated naturally-occurring unsaturated fatty alcohol.Alternatively, the fatty alcohol may be a synthetic fatty alcohol, suchas those obtained from a petroleum source through one or more synthesisreactions. For example, the fatty alcohol may be produced through theoligomerization of ethylene derived from a petroleum source or throughthe hydroformylation of alkenes followed by hydrogenation of thehydroformylation reaction product.

As shown in Equation 2, the reaction product may have the generalchemical formula R—(OCH₂CH₂)_(x)—OH, where R is a saturated orunsaturated, linear or branched hydrocarbyl group having from 10 to 20carbon atoms. According to some embodiments, the R group may be aniso-tridecyl group (—C₁₃H₂₇), as depicted in Chemical Structure A. Itshould be understood that Chemical Structure A depicts one possibleembodiment of the alcohol surfactant of Formula (I) in which the R groupis an iso-tridecyl group, which is used as a non-limiting example. Insome embodiments, Chemical Structure (A) may have 8 ethoxy groups (thatis, x equals 8 in Chemical Structure (A)) such that the alcoholsurfactant is a tridecyl alcohol ethyoxylate with an 8:1 molar ratio ofethylene oxide condensate to branched isotridecyl alcohol having thechemical formula C₁₃H₂₇—(OCH₂CH₂)₈—H.

Generally, an x:1 molar ratio of the fatty alcohol to the ethylene oxidemay be utilized to control the level of ethoxylation in Equation 2. Insome embodiments, x may be from 1 to 10, such as 1, 2, 3, 4, 5, 6, 7, 8,9, or 10. In some embodiments, the alcohol surfactant may be thereaction product of fatty alcohol ethoxylated with ethylene oxide at an8:1 molar ratio of fatty alcohol to ethylene oxide. In some particularembodiments, the alcohol surfactant may be a synthetic alcohol oxylateand may be an ethylene oxide condensate of isotridecyl alcohol. Thealcohol surfactant may be produced by an 8:1 molar ratio of ethyleneoxide to isotridecyl alcohol. In some particular embodiments, thealcohol surfactant may be produced by an 8:1 molar ratio of ethyleneoxide condensate to synthetic branched isotridecyl alcohol.

Finally, as previously mentioned, embodiments of the cement slurry mayinclude a carboxylic acid having from 16 to 18 carbon atoms. Thecarboxylic acid refers to any acids having the formula ROOH in which Ris a saturated or unsaturated, linear, or branched hydrocarbyl groupcomprising from 16 to 18 carbons, such as a hydrocarbyl group having 16carbons, 17 carbons, or 18 carbons. Examples of suitable carboxylicacids include palmitic acid, palmitoleic acid, vaccenic acid, oleicacid, elaidic acid, linoleic acid, α-linolenic acid, γ-linolenic acid,stearidonic acid, and combinations thereof.

In some embodiments, the cement slurry may contain from 0.1% BWOC to 10%BWOC of the carboxylic acid based on the total weight of the cementslurry. The cement slurry may contain from 0.02 to 90 lb/bbl of thecarboxylic acid based on the total weight of the cement slurry. Forinstance, the cement slurry may contain from 0.1 to 90 lb/bbl, from 0.1to 75 lb/bbl, from 0.1 to 50 lb/bbl, from 1 to 90 lb/bbl, from 1 to 50lb/bbl, from 5 to 90 lb/bbl, or from 5 to 50 lb/bbl of the carboxylicacid.

Without being bound by any particular theory, the carboxylic acid andthe alcohol surfactant may work together synergistically to controlfluid loss in the cement slurry. The combination of the carboxylic acidwith the alcohol surfactant may be used to affect the viscosity of thecement slurry. Moreover, the combination of the carboxylic acid with thealcohol surfactant may have retardation effects, meaning that thecombination may affect the time required to set or harden the cementslurry into a cured cement. The combination may also improve the densityand compressive strength of the cured cement. The alcohol surfactant mayreduce the surface tension of the aqueous phase of the cement slurry,reducing the fluid lost by the cement slurry. Additionally, thecarboxylic acid may further reduce the fluid loss of the cement slurryby plugging the pores of the cement filter cake, minimizing space forthe water or other fluids to escape from the cement.

In some embodiments, the cement slurry may contain one or moreadditives. The one or more additives may be any additives known to besuitable for cement slurries. As non-limiting examples, suitableadditives may include accelerators, retarders, extenders, weightingagents, fluid loss control agents, lost circulation control agents,other surfactants, antifoaming agents, specialty additives, andcombinations of these.

In some embodiments, the cement slurry may contain from 0.1 BWOC % to10% BWOC of the one or more additives based on the total weight of thecement slurry. The cement slurry may contain from 0.02 to 90 lb/bbl ofthe one or more additives based on the total weight of the cementslurry. For instance, the cement slurry may contain from 0.1 to 90lb/bbl, from 0.1 to 75 lb/bbl, from 0.1 to 50 lb/bbl, from 1 to 90lb/bbl, from 1 to 50 lb/bbl, from 5 to 90 lb/bbl, or from 5 to 50 lb/bblof the one or more additives.

In some embodiments, the one or more additives may include a dispersantcontaining one or more anionic groups. For instance, the dispersant mayinclude synthetic sulfonated polymers, lignosulfonates with carboxylategroups, organic acids, hydroxylated sugars, other anionic groups orcombinations of any of these. Without being bound by any particulartheory, in some embodiments, the anionic groups on the dispersant may beadsorbed on the surface of the cement particles to impart a negativecharge to the cement slurry. The electrostatic repulsion of thenegatively charged cement particles may allow the cement slurry to bedispersed and more fluid-like, improving flowability. This may allow forturbulence at lower pump rates, reduce friction pressure when pumping,reduce water content and may improve the performance of fluid lossadditives.

In some embodiments, one or more additives may alternatively oradditionally include a fluid loss additive. In some embodiments, thecement fluid loss additive may include non-ionic cellulose derivatives.In some embodiments, the cement fluid loss additive may behydroxyethylcellulose (HEC). In other embodiments, the fluid lossadditive may be a non-ionic synthetic polymer, for instance, polyvinylalcohol or polyethyleneimine. In some embodiments, the fluid lossadditive may be an anionic synthetic polymer, such as2-acrylamido-2-methylpropane sulfonic acid (AMPS) or AMPS-copolymers,including lattices of AMPS-copolymers. In some embodiments, the fluidloss additive may include bentonite, which may additionally viscosifythe cement slurry and may, in some embodiments, cause retardationeffects.

In some embodiments, the cement slurry may contain from 0.1% BWOC to 10%BWOC of one or more fluid loss additives, the one or more dispersants,or both. The cement slurry may contain from 0.02 to 90 lb/bbl of thefluid loss additives, the one or more dispersants, or both based on thetotal weight of the cement slurry. For instance, the cement slurry maycontain from 0.1 to 90 lb/bbl, from 0.1 to 75 lb/bbl, from 0.1 to 50lb/bbl, from 1 to 90 lb/bbl, from 1 to 50 lb/bbl, from 5 to 90 lb/bbl,or from 5 to 50 lb/bbl of the fluid loss additives, the one or moredispersants, or both.

Embodiments of the disclosure also relate to methods of producing thecement slurries previously described. In some embodiments, the methodfor producing a cement slurry may include mixing water with a cementprecursor material, an alcohol surfactant having from 10 to 20 carbonatoms, and a carboxylic acid having an aliphatic chain comprising from16 to 18 carbon atoms to produce a cement slurry. As previouslydescribed, the alcohol surfactant may have the formula R—(OC₂H₄)_(x)—OHin which R is a hydrocarbyl group having from 10 to 20 carbon atoms andx is an integer from 1 to 10. In some embodiments, the alcoholsurfactant may have an HLB of from 12 to 13.5. The water, cementprecursor material, alcohol surfactant, and carboxylic acid may be inaccordance with any of the embodiments previously described. The cementslurry may include one or more additives, including but not limited todispersants and fluid loss additives.

As previously mentioned, the combination of the carboxylic fatty acidwith the alcohol surfactant may have retardation effects, meaning thatthe combination may affect the time required to set or harden the cementslurry into a cured cement. The combination may also improve the densityand compressive strength of the cured cement. This may allow for uniformplacement of the cement slurry, optimal curing conditions (such ascuring time and water loss) and may produce a strong, dense curedcement.

The mixing step, in some embodiments, may involve shearing the water,cement precursor material, surfactant, and, optionally, other additivesat a suitable speed for a suitable period of time to form the cementslurry. In one embodiment, the mixing may be done in the lab using astandard API blender. 15 seconds at 4,000 RPM and 35 seconds at 12,000RPM, The equation of mixing energy is:

$\begin{matrix}{\frac{E}{M} = \frac{k\; \omega^{2}t}{V}} & \left( {{Equation}\mspace{14mu} 3} \right)\end{matrix}$

Where

E=Mixing energy (kJ)M=Mass of slurry (kg)k×6.1×10⁻⁸ m⁵/s (constant found experimentally)ω=Rotational speed (radians/s)t=Mixing time (s)V=Mixing time (s)V=Slurry volume (_(m) ³)

Further embodiments of the present disclosure relate to methods of usingthe cement slurries previously described. In some embodiments, themethod may include pumping the cement slurry into a location to becemented, and curing the cement slurry. The location to be cemented may,for instance, be a well, a wellbore, an annulus, or other suchlocations.

Cementing is performed when the cement slurry is deployed into the wellvia pumps, displacing the drilling fluids still located within the well,and replacing them with cement. The cement slurry flows to the bottom ofthe wellbore through the casing, which will eventually be the pipethrough which the hydrocarbons flow to the surface. From there, thecement slurry fills in the space between the casing and the actualwellbore, and hardens. This creates a seal so that outside materialscannot enter the well flow, as well as permanently positions the casingin place. In preparing a well for cementing, it is important toestablish the amount of cement required for the job. This may be done bymeasuring the diameter of the borehole along its depth, using a caliperlog. Utilizing both mechanical and sonic means, multi-finger caliperlogs measure the diameter of the well at numerous locationssimultaneously in order to accommodate for irregularities in thewellbore diameter and determine the volume of the openhole.Additionally, the required physical properties of the cement areessential before commencing cementing operations. The proper set cementis also determined, including the density and viscosity of the material,before actually pumping the cement into the hole.

As used throughout the disclosure, “curing” refers to providing adequatemoisture, temperature and time to allow the concrete to achieve thedesired properties (such as hardness) for its intended use through oneor more reactions between the water and the cement precursor material.In contrast, “drying” refers to merely allowing the concrete to achievea moisture condition appropriate for its intended use, which may onlyinvolve physical state changes, as opposed to chemical reactions. Insome embodiments, curing the cement slurry may refer to passivelyallowing time to pass under suitable conditions upon which the cementslurry may harden or cure through allowing one or more reactions betweenthe water and the cement precursor material. Suitable conditions may beany time, temperature, pressure, humidity, and other appropriateconditions known in the cement industry to cure a cement composition. Insome embodiments, suitable curing conditions may be ambient conditions.Curing may also involve actively hardening or curing the cement slurryby, for instance, introducing a curing agent to the cement slurry,providing heat or air to the cement slurry, manipulating theenvironmental conditions of the cement slurry to facilitate reactionsbetween the water and the cement precursor, a combination of these, orother such means. Usually, the cement will be cured and convert fromliquid to solid due to formation conditions, temperature, and pressure.In the laboratory high temperature and high pressure curing chamber isused for curing the cement specimens at required conditions. Cubicalmolds (2″×2″×2″) and cylindrical cells (1.4″ diameter and 12″ length)were lowered into the curing chamber. Pressures and temperatures weremaintained until shortly before the end of the curing where they werereduced to ambient conditions.

In some embodiments, curing may occur at a relative humidity of greaterthan or equal to 80% in the cement slurry and a temperature of greaterthan or equal to 50° F. for a time period of from 1 to 14 days. Curingmay occur at a relative humidity of from 80% to 100%, such as from 85%to 100%, or 90% to 100%, or from 95% to 100% relative humidity in thecement slurry. The cement slurry may be cured at temperatures of greaterthan or equal to 50° F., such as greater than or equal to 75° F.,greater than or equal to 80° F., greater than or equal to 100° F., orgreater than or equal to 120° F. The cement slurry may be cured attemperatures of from 50° F. to 250° F., or from 50° F. to 200° F., orfrom 50° F. to 150° F., or from 50° F. to 120° F. In some instances, thetemperature may be as high as 500° F. The cement slurry may be cured forfrom 1 day to 14 days, such as from 3 to 14 days, or from 5 to 14 days,or from 7 to 14 days, or from 1 to 3 days, or from 3 to 7 days.

Further embodiments of the present disclosure relate to particularmethods of cementing a casing in a wellbore. The method may includepumping a cement slurry into an annulus between a casing and a wellboreand curing the cement slurry. The cement slurry may be in accordancewith any of the embodiments previously described. Likewise, curing thecement slurry may be in accordance with any of the embodimentspreviously described. As stated above, Cementing is performed when thecement slurry is deployed into the well via pumps, displacing thedrilling fluids still located within the well, and replacing them withcement. The cement slurry flows to the bottom of the wellbore throughthe casing, which will eventually be the pipe through which thehydrocarbons flow to the surface. From there it fills in the spacebetween the casing and the actual wellbore, and hardens. This creates aseal so that outside materials cannot enter the well flow, as well aspermanently positions the casing in place.

Embodiments of the disclosure also relate to methods of producing curedcements. The method may include combining water with a cement precursormaterial, at least one alcohol surfactant having from 10 to 20 carbonatoms, and a carboxylic acid having an aliphatic chain with 16 to 18carbons, to produce a cement slurry. The cement slurry, including thecement precursor material, water, alcohol surfactant, and carboxylicacid all may be in accordance with any of the embodiments previouslydescribed. The method may include curing the cement slurry by allowingfor a reaction between the water and the cement precursor material toproduce cured cement. The curing step may be in accordance with any ofthe embodiments previously described.

Embodiments of the disclosure also relate to cured cement compositions.The cured cement include an alcohol surfactant having from 10 to 20carbon atoms, and a carboxylic acid having from 16 to 18 carbon atoms.The alcohol surfactant and carboxylic acid may be in accordance with anyof the embodiments previously described. The cured cement may haveimproved properties, including but not limited to hardness and densityas a result of the synergistic effects of the alcohol surfactant and thecarboxylic fatty acid. In some embodiments, cement is composed of fourmain components: tricalcium silicate (Ca₃O₅Si) which contributes to theearly strength development: dicalcium silicate (Ca₂SiO₄), whichcontributes to the final strength, tricalcium aluminate (Ca₃Al₂O₆),which contributes to the early strength; and tetracalcium aluminaferrite. These phases are sometimes called alite and beliterespectively. In addition, gypsum may be added to control the settingtime of cement.

In one embodiment, the silicates phase in cement may be about 75-80% ofthe total material. Ca₃O₅Si is the major constituent, with concentrationas high as 60-65%. The quantity of Ca₂SiO₄normally does not exceed 20%(except for retarded cements). The hydration products for Ca₃O₅Si andCa₂SiO₄ are calcium silicate hydrate (Ca₂H₂O₅Si) and calcium hydroxide(Ca(OH)₂), also known as Portlandite. The calcium silicate hydratecommonly called CSH gel has a variable C:S and H:S ratio depending onthe temperature, Calcium concentration in the aqueous phase, and thecuring time. The CSH gel comprises +/−70% of fully hydrated Portlandcement at ambient conditions and is considered the principal binder ofhardened cement. By contrast, the calcium hydroxide is highlycrystalline with concertation of about 15-20 wt. % and is the reason forthe high pH of cement. Upon contact with water, the gypsum may partiallydissolves releasing calcium and sulphate ions to react with thealuminate and hydroxyl ions produced by the C3A to form a calciumtrisulphoaluminate hydrate, known as the mineral Ettringite(Ca₆Al₂(SO₄)₃(OH)₁₂.26H₂O) that will precipitate onto the Ca₃O₅Sisurfaces preventing further rapid hydration (flash-set). The gypsum isgradually consumed and ettringite continues to precipitate until thegypsum is consumed. The sulphates ion concentration will be drop downand the ettringite will become unstable converting to calciummonosulphoaluminate hydrate (Ca₄Al₂O₆(SO₄).14H₂O). The remainingunhydrated Ca₃O₅Si will form calcium aluminate hydrate. Cement slurrydesign is based on the altering or inhibition of the hydration reactionswith specific additives.

The cured cement may include one or more of calcium hydroxide,silicates, oxides, belite (Ca₂SiO₅), alite (Ca₃SiO₄), tricalciumaluminate (Ca₃Al₂O₆), tetracalcium aluminoferrite (Ca₄Al₂Fe₂O₁₀),brownmilleriate (4CaO.Al₂O₃.Fe₂O₃), gypsum (CaSO₄.2H₂O) sodium oxide,potassium oxide, limestone, lime (calcium oxide), hexavalent chromium,calcium alluminate, other similar compounds, and combinations of these.The cement precursor material may include Portland cement, siliceous flyash, calcareous fly ash, slag cement, silica fume, any known cementprecursor material or combinations of any of these.

The cured cement may contain from 0.1 to 10% BWOC of the at least onealcohol surfactant based on the total weight of the cured cement. Thecured slurry may contain from 0.02 to 90 lb/bbl of the surfactant basedon the total weight of the cured cement. For instance, the cured cementmay contain from 0.1 to 90 lb/bbl, from 0.1 to 75 lb/bbl, from 0.1 to 50lb/bbl, from 1 to 90 lb/bbl, from 1 to 50 lb/bbl, from 5 to 90 lb/bbl,or from 5 to 50 lb/bbl of the surfactant.

In some embodiments, the cured cement may contain from 0.1 wt. % to 10wt. % of the carboxylic acid based on the total weight of the curedcement. The cement may contain from 0.02 to 90 lb/bbl of the carboxylicacid based on the total weight of the cement. For instance, the cementmay contain from 0.1 to 90 lb/bbl, from 0.1 to 75 lb/bbl, from 0.1 to 50lb/bbl, from 1 to 90 lb/bbl, from 1 to 50 lb/bbl, from 5 to 90 lb/bbl,or from 5 to 50 lb/bbl of the carboxylic acid.

The cured cement may contain from 0.1% BWOC to 10% BWOC of one or moreadditives based on the total weight of the cured cement. The one or moreadditives may include accelerators, retarders, extenders, weightingagents, fluid loss control agents, lost circulation control agents,other surfactants, antifoaming agents, specialty additives, andcombinations of these. The cement may contain from 0.02 to 90 lb/bbl ofthe one or more additives based on the total weight of the cement. Forinstance, the cement may contain from 0.1 to 90 lb/bbl, from 0.1 to 75lb/bbl, from 0.1 to 50 lb/bbl, from 1 to 90 lb/bbl, from 1 to 50 lb/bbl,from 5 to 90 lb/bbl, or from 5 to 50 lb/bbl of the one or moreadditives.

Without being bound by any particular theory, controlling the fluid lossand rheology properties of the cement slurry when producing the curedcement may result in a stronger, more stable cured cement, as previouslydiscussed. In some embodiments, the cured cement of the presentdisclosure may have a compressive strength of from 400 to 5000 psi. inthe compressive Strength Test. In the test, the set cement cubes wereremoved from the molds, and placed in a hydraulic press where increasingforce was exerted on each cubes until failure. The hydraulic presssystem used in this study applied known compressive loads to thesamples. This system was designed to test the compressive strength ofsample cement cubes in compliance with API specifications for oil wellscement testing.

Similarly, the cured cement produced may have a higher density thanconventional cements, which may not cure as uniformly, due to the issuespreviously described, such as rheology and fluid loss. In someembodiments, the cured cement may have a density of from 70 pounds percubic foot (1b/f³) to 160 lb/f³.

In some embodiments, the cement slurry of the present disclosure mayhave improved rheological properties, such as viscosity. The cementslurry may have a viscosity as measured using a Fann 35 rheometeraccording to American Petroleum Institute Specification RP 13B at 600rotations per minute (RPM) of less than 100 after 10 minutes. In someembodiments, the cement slurry may have a rheology reading at 600 RPM ofless than or equal to 95, such as less than or equal to 90 after 10minutes. In some embodiments, the cement slurry may have a viscosity at600 RPM of from 75 to 100, or 75 to 95, or 80 to 95, or 80 to 90, or 80to 100, or 85 to 100, after 10 minutes.

The cured cement composition may additionally have improved wettabilityproperties. Wettability refers to the tendency for fluid to spread outon or adhere to a solid surface in the presence of other immisciblefluids. Without being bound by any particular theory, cement slurriesand cured cement compositions having high wettability may reduce therisk of cement contamination and bonding problems to ensure a strongbong as the cement slurry is cured or dried into cured cement. This mayproduce a stronger annular seal between the annulus and the curedcement, as previously described.

In some embodiments, the cement slurry may contain water and may bewater-based. As such, the cement slurry may by hydrophilic, formingstronger bonds with water-wet surfaces. Well sections drilled withnon-aqueous drilling fluids may have oil-wet surfaces, resulting in poorbonding between the well and the cement slurry, as oil and waternaturally repel. Poor bonding may lead to poor isolation and a buildupof unwanted casing-casing or tubing-casing annular pressure. In someembodiments, the addition of the alcohol surfactant to the cementslurry, the cured cement composition, or both, may address thesedifficulties to provide a better bond by rendering the well surface morewater wet. Without being bound by theory, it is desirable to make theformation or/and casing water wet to enhance and improve the bondingbetween cement and casing and cement and formation. If the wettabilityof the formation or casing is oil wet not water wet then the bondingwill be poor and could result in small gap(s) or channel(s) between thecement and casing or the cement and formation thereby resulting inimproper wellbore isolation. This improper wellbore isolation could leadto fluid or gas escaping from the well through this gas or channel dueto de-bonding.

As a non-limiting example, to perform a wettability test, casing couponsused in the test may be a piece of metal taken as a sample from thetubulars that will be cemented downhole. A piece of Teflon tape may beplaced down the center of the casing coupon to provide a standard for acomplete oil-wet surface To the left of the Teflon tape strip, thecasing metal coupon is present while the side to the right of the tapeis left unwashed. The washing is performed using surfactant. The side ofcasing coupon is washed in a viscometer cup filled with the specifiedsurfactant solution. The viscometer is rotated at 100 RPM for 30 min andat a temperature of 140° F. A water droplet may be placed in each of thethree sections. The droplet may be visually observed after a period oftime, after undergoing a variety of conditions, or after a combinationof both to determine the wettability. The same test procedure may beperformed with a piece of cured cement composition in place of thecasing coupon metal.

The droplet on the Teflon surface may not absorb into the cement butrather may maintain a contact angle with the test surface of from 120°to 180°. The droplet on the Teflon surface should consistently displaypoor wettability and can be used as a control sample. To the left andright of the Teflon strip, the water droplet may completely absorb intothe cement, partially absorb into the cement, may spread out onto thecured cement, or may maintain its spherical droplet nature based on howwater-wet the cement is. In some embodiments, a droplet having a contactangle of greater than 90° may be considered cement having poor waterwettability. A droplet having a contact angle of less than 90° butgreater than or equal to 35° may be considered cement having fairwettability. Finally, if the droplet has a contact angle of less than35° the cement may have good wettability. Water wettability may beinversely related to oil wettability. That is, if a water droplet isrepelled by the cement, it may be an indication that the cement ishydrophobic and may have good oil-wettability, or an affinity for oil.

As mentioned, the droplet may be observed under a variety of conditions.In some embodiments, the wettability of the cured cement, and/or thewettability of the casing coupon may be observed after preheating thecement for 30 minutes at a temperature of 140° F. Likewise, the cementmay be immersed in an oil based mud for 10 minutes and the wettabilitymay be observed. In some embodiments, the cement may be attached to arotor or a viscometer cup and may be immersed in a spacer fluid suchthat at least about two thirds of the cement is immersed in the fluid.The cement is immersed while being attached to a side of viscometer cupto insure it remains static while the fluid is being stirred by theviscometer rotation The cement may be rotated at 100 rotations perminute (RPMs) for 30 minutes and the wettability determined. Theintention of dipping the sample in oil based mud is to insure that thesample is “oil-wet”. Oil wet samples will show a specific contact anglewith water (<90°). After that, the same sample may dipped in surfactantto try and convert it to being “water-wet”. Water wet samples will showa different contact angle (>)90°. If the surfactant is successful, itwill be able to convert the sample into being a water-wet and this willbe shown from the contact angle variations.

EXAMPLES

Rheology testing was conducted on various formulations of the cementslurry of the present embodiments as compared to conventional cementslurries. Testing was conducted regarding the fluid loss properties ofvarious cement slurries. The compositions of each of the samples testedare listed below in Table 1. Example 1 contained 118 pounds per cubicfeet (pcf) of Portland G cement along with one gram (g) of retardercalcium lignosulfonate salt commercially available from any cementservice companies for example Schlumberger, Halliburton or Baker HughesIncorporated, and 2 g of an 8:1 molar ratio of ethylene oxide condensateof synthetic branched isotridecyl alcohol as the surfactant. The slurryincluded 44% BWOC.

Comparative Example 1 was a composition containing only cement andwater. Comparative Example 2 was a composition containing cement, acarboxylic acid having only 12 to 14 carbons, and an 8:1 molar ratio ofethylene oxide condensate of synthetic branched isotridecyl alcohol.Comparative Example 3 was a composition that included cement, a 16 to 18carbon carboxylic acid and a surfactant having a 1:1 ratio of ethyleneoxide condensate of a fatty alcohol chain having from 12 to 14 carbons.Finally, Comparative Example 4 was a formulation having cement, acarboxylic acid having from 12 to 14 carbons, and L1as the surfactant,as described infra.

TABLE 1 Cement Slurry Compositions Sample Composition Example 1 118pounds per cubic feet (pcf) cement 2 g C16-C18 Alkyl carboxylic acid,100% fatty acids (Melting point 91.4 to 125.6 F.) and boiling point of392 to 437 F. It is a colorless solid form having a density of 0.93 to0.95 g/cm3 and viscosity of 30 to 35 cp. 2 g (C₁₃H₂₇(OCH₂CH₂)₈OH)Comparative 118 pcf cement Example 1 Comparative 118 pcf cement Example2 2 g C12-C14 Saudi Arabia Fatty Acid (C12-C14) (see parameters below)Saudi Arabia Fatty Acid (C12-C14) Parameter Value Lauric Acid 70-78%Form Solid Flash Point 266 F. Density   0.84 g/cm3 2 g(C₁₃H₂₇(OCH₂CH₂)₈OH) Comparative 118 pcf cement Example 3 2 g C16-C18Saudi Arabia Fatty Acid (C12-C14) (see parameters below) Saudi ArabiaFatty Acid (C16-C18) Parameter Value Fatty acids, C16-C18 100% FormSolid Boiling point 392 to 437 F.    Flash Point 217.4 F.   Density 0.93to 0.95 g/cm3 Auto-ignition 662 F. temperature 2 g C12-C14 Saudi ArabiaFatty Acid (C12-C14) (see supra) Comparative 118 pcf cement Example 4 2g C12-C14 Saudi Arabia Fatty Acid (C12-C14) (see supra) 2 g L1 anonionic surfactant composed of eight moles ethylene oxide condensate ofsynthetic branched iso tridecyl alcohol (C₁₃H₂₇(OCH₂CH₂)₈OH) produceddirectly from Saudi petrochemicals. The value for theHydrophilic-Lipophilic Balance (HLB) for this surfactant is 4.7, itsdensity is 0.905, and it has a Hydrophilic-Lipophilic Balance (HLB) of12.75.

The amount of fluid loss for each sample was tested, the results ofwhich are listed in Table 2. The Stirring Fluid Loss Test Assembly isequipped with a stirrer to simulate circulation and a heating jacket tosimulate the bottomhole circulating temperature (BHCT). The pressuredifferential between annular and formation pressure is simulated bypressurized nitrogen. A 325 micron mesh screen (or a porous core) and afiltration chamber simulate the permeable zone. A control panel allowsprecise setting and controlling of the temperature and pressure.Operators use this instrument to perform standard tests outlined in theAmerican Petroleum Institute (API) Recommended Practice (RP) for TestingWell Cements, API RP 10B-2.

TABLE 2 Fluid Loss Results Fluid Loss Sample Duration (mL) Example 11800 seconds (30 mins) 11.5 Comparative Example 1 45 seconds 75Comparative Example 2 240 seconds (4 mins) 66 Comparative Example 3 42seconds 72 Comparative Example 4 72 seconds (1 min, 12 56 seconds) 56

As previously mentioned, use of the alcohol surfactant in combinationwith the cement precursor material and water may aid in reducing fluidloss in the cement slurry. Without being bound by any particular theory,it is believed that the alcohol surfactant may reduce the surfacetension of the aqueous phase of the cement slurry, thus reducing thefluid lost by the slurry. Additionally, in embodiments in which thecement slurry comprises both the alcohol surfactant and a carboxylicacid having from 16 to 18 carbon atoms, the carboxylic acid may furtherreduce the fluid loss of the cement slurry by plugging the pores of thecement filter cake, which may minimize space for the aqueous phase toescape from the slurry.

Different oil and drilling operations may require use of cement slurrieswith particular fluid loss requirements. For instance, for operations toprevent gas channeling, cement slurries must have a fluid loss of lessthan 30 to 50 mL/30 minutes (mins). Linear cementing and horizontal wallcementing require a cement slurry with a fluid loss of less than 50mL/30 mins. Casing cementing requires a cement slurry with a fluid lossbetween 200 and 300 mL/30 mins. High density slurries may require lessthan 50 mL/30 mins. Some operations may require different cementslurries depending on the formation. For example, squeeze cementing witha formation permeability of less than 1 millidarcy (md) may require acement slurry with a fluid loss of less than 200 mL/30 mins, whileformation permeabilities between 1 and 100 md require between 100 and200 mL/30 mins, and formations greater than 100 md require between 35and 100 mL/30 mins.

Example 1 of the present disclosure showed a fluid loss after 30 minutes(18000 seconds) of only 11.5 mL/30 mins, which meets the requirements ofeven the strictest drilling operations, which typically require lessthan or equal to 30 mL/30 minute fluid loss rates. The closestcomparative examples include Comparative Example 2, which also contained2 g of an 8:1 molar ratio of ethylene oxide condensate of syntheticbranched iso tridecyl alcohol, however, combined with a different fattyacid. However, Comparative Example 2 exhibited a fluid loss of 66 mLafter only 4 minutes. Similarly, Comparative Example 3, which containedthe same fatty acid but a different surfactant, exhibited 72 mL of fluidloss after only 42 seconds. As shown in the Table, Example 1, the cementslurry of the present disclosure, outperformed all of the comparativesamples, Comparative Examples 1, 2, 3, and 4.

The following description of the embodiments is illustrative in natureand is in no way intended to be limiting it its application or use. Asused throughout this disclosure, the singular forms “a,” “an” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a” component includes aspects havingtwo or more such components, unless the context clearly indicatesotherwise.

It should be apparent to those skilled in the art that variousmodifications and variations may be made to the embodiments describedwithin without departing from the spirit and scope of the claimedsubject matter. Thus, it is intended that the specification cover themodifications and variations of the various embodiments described withinprovided such modification and variations come within the scope of theappended claims and their equivalents.

It is noted that one or more of the following claims utilize the term“where” as a transitional phrase. For the purposes of defining thepresent technology, it is noted that this term is introduced in theclaims as an open-ended transitional phrase that is used to introduce arecitation of a series of characteristics of the structure and should beinterpreted in like manner as the more commonly used open-ended preambleterm “comprising.”

Having described the subject matter of the present disclosure in detailand by reference to specific embodiments of any of these, it is notedthat the various details disclosed within should not be taken to implythat these details relate to elements that are essential components ofthe various embodiments described within, even in cases where aparticular element is illustrated in each of the drawings that accompanythe present description. Further, it should be apparent thatmodifications and variations are possible without departing from thescope of the present disclosure, including, but not limited to,embodiments defined in the appended claims. More specifically, althoughsome aspects of the present disclosure are identified as particularlyadvantageous, it is contemplated that the present disclosure is notnecessarily limited to these aspects.

What is claimed is:
 1. A cured cement comprising: an alcohol surfactantcomprising ethylene oxide condensate of branched isotridecyl alcoholhaving the formula:R—(OC₂H₄)_(x)—OH where x is an integer from 1 and 10, and a carboxylicacid comprising an aliphatic carbon chain having from 16 to 18 carbonatoms.
 2. The cured cement of claim 1, where the alcohol surfactant hasa hydrophilic -lipophilic balance (HLB) of from 12 to 13.5.
 3. The curedcement of claim 1, where the cured cement contains from 10 to 70% BWOC(By Weight of Cement) water.
 4. The cured cement of claim 1, where thecured cement contains from 0.1 to 10% BWOC of the alcohol surfactant. 5.The cured cement of claim 1, where the cured cement contains from 0.1 to10% BWOC of the carboxylic acid.
 6. The cured cement of claim 1, wherethe carboxylic acid is selected from the group consisting of palmiticacid, palmitoleic acid, vaccenic acid, oleic acid, elaidic acid,linoleic acid, α-linolenic acid, γ-linolenic acid, stearidonic acid, orcombinations thereof.
 7. The cured cement of claim 1, where the curedcement comprises a hydraulic cement.
 8. The cured cement of claim 1,where the cured cement comprises a non-hydraulic cement.
 9. The curedcement of claim 1, where the cured cement comprises one or morecomponents selected from the group consisting of calcium hydroxide,silicates, belite (Ca₂SiO₅), alite (Ca₃SiO₄), tricalcium aluminate(Ca₃Al₂O₆), tetracalcium aluminoferrite (Ca₄Al₂Fe₂O₁₀), brownmillerite(4CaO.Al₂O₃.Fe₂O₃), gypsum (CaSO₄.2H₂O), lime (calcium oxide), calciumaluminate, or combinations thereof.
 10. The cured cement of claim 1,where the cured cement comprises Portland cement, siliceous fly ash,calcareous fly ash, slag cement, or combinations thereof.
 11. The curedcement of claim 1, where x is from 5 to 10.